Mixing performance of the mixing section in a pin barrel extruder

3-D isothermal flow fields of rubber melts in the pin and pitiless mixing sections were simulated by FEM. Mixing performance of the two models is compared by particle tracking analysis. Simulation results indicate that the path lines of the melts in the pin mixing section are disturbed locally. The stagnant melts are broken up. The flow fields are divided into six zones by the six pins. The direction of melt flow is changed. The velocity gradients of melt increase. The shear stress increases with the increment of velocity gradient. The distribution of the mixing index is even. Average segregation scale of the eleven slices on the model with pins is 10% lower than that of the pinless case. Barrel pins strengthened the dispersive mixing. The mixing performance of the pin extruder is better than that of the pinless case.